UNIVERSITY    OF   CALIFORNIA  AGRICULTURAL     EXPERIMENT     STATION 

COLLEGE    OF    AGRICULTURE  benj.  ide  wheeler,  president 

BERKELEY,  CALIFORNIA  THOMAS  roRSYTH  HUNT-  °"N  A~°  "'""'" 


CIRCULAR  No.  91 


DISINFECTION  ON  THE  FARM. 

By   C.  M.  Haeing. 

Disease  producing  bacteria,  such  as  those  causing  tuberculosis 
and  infectious  abortion  in  cattle,  and,  in  fact,  most  all  of  the  infect- 
ing organisms  causing  diseases  in  animals,  are  quite  readily  destroyed 
by  the  use  of  certain  chemicals  which  are  more  effectively  applied 
under  the   conditions   mentioned  herein. 

1.  Clean  the  stable  and  corrals  thoroughly.  Cleanliness  is  an 
important  adjunct  to  the  work  of  disinfection.  The  proper  clean- 
ing of  the  stable  would  include  (a)  the  removal  of  all  manure; 
(6)  the  removal  of  all  feed  and  piles  of  foreign  material  where  disin- 
fection is  to  be  applied;  (c)  the  removal  of  rotten  woodwork  and 
loose  boards,  especially  of  the  floors;  (d)  the  sprinkling  of  the  floor 
and  dirty  surfaces  with  a  disinfectant  to  lay  the  dust,  and  the 
sweeping  of  the  ceilings,  walls  and  floors  thoroughly;  (e)  the  removal 
of  all  dried  accumulations  of  foreign  material  about  the  mangers, 
floors  and  drains.  In  dairy  barns  it  is  especially  important  to  scrape 
the  side  walls  in  order  to  remove  all  manure;  (f)  Special  attention 
should  always  be  given  to  the  feed  boxes,  mangers,  and  water 
troughs,  as  it  is  through  these  that  the  infecting  material  of  tuber- 
culosis, especially,  is  most  apt  to  be  carried  from  the  diseased  to  the 
healthy  animal;  (g)  In  cleaning  the  corral  all  refuse,  manure,  etc., 
should  be  removed  to  a  place  inaccessible  to  live  stock.  The  sur- 
face of  the  corral  can  be  successfully  cleaned  by  scraping;  (h)  In 
the  proper  disinfection  of  cow  yards  after  removing  all  particles  of 
manure,  the  surface  can  be  made  safe  with  slight  expense  by  burn- 
ing over  the  surface  with  a  thin  layer  of  straw,  or  other  cheap 
material,  followed  by  plowing  under  the  top  soil. 

2.  Permit  the  entrance  of  a  plentiful  amount  of  light.  Strong  sun- 
light is  a  natural  germ  destroyer,  providing  the  sun  shines  directly 
upon  the  infecting  material  sufficiently  to  dry  it  completely.  These 
organisms  are  destroyed  by  less  intense  light,  but,  of  course,  more 
slowly  than  where  direct  sunlight  is  possible,  consequently  bacteria 
live  for  long  periods  in  dark  places. 

3.  Apply  chemical  disinfectants.  After  the  stable  and  yards  have 
been  treated  as  recommended  above,  they  are  ready  for  the  applica- 
tion of  chemical  disinfectants.  These  are  substances  which  poison 
the  bacteria  which  are  apt  to  be  very  numerous  where  an  infectious 
disease   exists.     Many   different   disinfectants   can   be  used,   but  we 

(l) 


limit  ourselves  here  to  the  use  of  two  preparations,  corrosive  sub- 
limate and  compound  solution  of  cresol,  which  are  among  the  most 
active  in  their  value  for  the  destruction  of'  these  organisms.  These 
materials  are  cheap  and  obtainable  at  any  drug  store. 

1.  Bichloride  of  mercury,  or  corrosive  sublimate.  This  is  a  most 
active  germicide  in  one  tenth  per  cent  solutions.  It  has  the  advan- 
tage over  cresol  for  use  in  a  dairy  stable  on  account  of  it  being  odor- 
less. This  substance  is  very  poisonous  when  taken  internally  and 
must  be  used  with  great  care.  Before  it  is  applied,  it  must  be  dis- 
solved in  water  in  the  proportion  of  one  part  to  one  thousand,  when 
purchased  in  the  powdered  or  crystal  form.  Corrosive  sublimate  is 
dispensed  by  druggists  in  tablets  which  dissolve  readily  in  cold 
water.  Tablets  colored  blue  are  preferable,  as  they  color  the  water 
and  lessen  the  danger  of  accidental  poisoning.  Directions  for  using 
the  tablets  in  a  one  to  one  thousand  per  cent  solution  are  usually 
printed  on  the  package  in  which  the  tablets  are  dispensed.  One 
ounce  of  corrosive  sublimate  crystals  dissolved  in  eight  gallons  of 
water  makes  a  solution  of  the  proper  strength.  In  making  this 
solution  the  corrosive  sublimate  crystals  should  be  dissolved  in  one 
gallon  of  hot  water  and  then  mixed  with  enough  cold  water  to  make 
eight  gallons.  It  corrodes  metal,  hence  the  solution  should  be  kept 
in  a  wooden  tub,  or  earthenware  crock. 

2.  Compound  solution  of  cresol.  Compound  solution  of  cresol 
(liquor  cresolis  eompositus  or  lysol),  now  recognized  by  the  U.  S. 
Pharmacopoeia  as  an  official  preparation,  is  composed  of  equal  parts  of 
cresol  (U.  S.  P.)  and  linseed  oil-potash  soap.  It  is  an  efficient  disin- 
fectant in  a  4  per  cent  solution  when  applied  to  infected  stable  sur- 
faces and  has  the  advantage  of  mixing  readily  with  water. 

Coal  tar  products  similar  to  the  above  cresol  preparations  which 
are  sold  under  various  trade  names  are  usually  satisfactory  when 
used  in  sufficient  strength.  As  stable  disinfectants  such  dips  should 
be  used  in  sufficient  strength  to  insure  a  cresylic  acid  solution  of 
at  least  2  per  cent. 

Mention  of  carbolic  acid  is  omitted  in  this  circular  because  the 
cresol  preparations  are  cheaper  than  the  pure  carbolic  acid  and  not 
so  poisonous.  Crude  carbolic  acid  varies  so  in  strength  that  it  is  not 
to  be  depended  upon. 

Many  of  the  commercial  disinfectants  are  inefficient  unless  used  in 
considerable  strength. 

Chemical  disinfectants  in  ordinary  strength  are  inefficient  in  an- 
thrax, blackleg,  and  hog  cholera.  Fire,  formaldehyde  in  10  per  cent 
solution,  concentrated  mineral  acids,  and  the  cresol  or  other  strong- 
preparation,  undiluted,  are  the  only  disinfectants  that  can  be  de- 
pended upon. 


—  3  — 

Disinfectants  cannot  destroy  germs  if  they  do  not  come  into  direct 
contact  with  them.  Disinfectants  should  be  applied  in  sufficient 
quantity  to  thoroughly  saturate  the  surfaces,  after  the  adhering 
particles  of  dirt  are  removed.  In  the  application  of  the  disinfectant 
in  cow  stables  it  is  well  to  use  a  broom  or  stiff  brush  and  thoroughly 
scrub  the  floor,  feed  troughs,  stanchions,  and  lower  parts  of  the  Avails. 
The  solution  can  be  applied  to  the  ceilings  and  upper  parts  of  the 
side  walls  with  a  spray  pump,  and  must  be  carried  into  any  crevice 
and  recess  into  which  dirt  can  enter. 

After  disinfecting,  whitewash  the  stable.  Although  whitewash  is 
not  an  active  disinfectant,  in  the  usual  meaning  of  the  term,  it  is  an 
excellent  purifier  and  should  in  all  cases  be  used  in  stables  after  they 
have  been  thoroughly  cleansed  and  disinfected  with  other  agents. 
Hot  whitewash  for  this  purpose  is  better  than  cold.  If  chloride  of 
lime  is  added  to  whitewash  in  the  proportion  of  four  ounces  to  the 
gallon,  the  value  of  this  application  is  greatly  increased.  It  is  advis- 
able to  whitewash  cow  stables  frequently,  at  least  once  in  six  months, 
and  better  every  three  months  where  diseased  animals  have  been  kept. 


